Understanding the Band Gap, Magnetism, and Kinetics of Graphene Nanostripes in Graphane

The electronic structure and kinetic stability of various graphene nanostripes (GNSs) in graphane are systematically studied by ab initio simulations. The band gap of armchair GNS (nonmagnetic) is determined by the quantum confinement of pi electrons and modified by the contraction of the edge C-C bonds. The band gap of zigzag GNS is induced by the exchange splitting of the edge states and its magnetism closely correlates with the long-range nature of pi electrons, quantum confinement, intraedge exchange interaction, and interedge superexchange interaction. The kinetic stability of these GNSs in graphane is probed by the potential barriers and reaction rates for the diffusion and desorption of the hydrogen adatoms at various graphene/graphane interfaces. These interfaces are very stable under conventional thermalization conditions. The conformation of graphane has a small effect on the electronic structure of GNS but has a significant effect on the kinetic stability of the interfacial adatoms. The hydrogen adatoms in the graphane bulk are much more stable than the interfacial ones, which implies the possibility to carve out sharp-edge GNSs in graphane. An approach is proposed to fabricate integrated field-effect transistors based on sharp-edge and substrate-decoupled GNSs in substrate-supported graphane.